Motherboard connections

When I used to build computers the cases used to come with single cables which you used to have to connect onto the motherboard. You could get double connectors onto the board (such as Power switch, or reset). Like:-
My question is, what are they called? Ideally the single ones (not double or triple connections like in the photo, I just couldn't find a picture of a single one)

I've got an alarm with connection pins on, and thought using these 'motherboard connectors' would be the ideal solution, and to connect the other end to a raspberry pi's connectors.

Who is Participating?

They are header connectors see here for examples. Electronics shops or PC shops should be able to get them for you. The 2 pin plugs are about $0.50 each & ideally need a crimping tool to fit the wires although you can use pliers. They can also be split so a 4 x 1 female connector can be broken into 2 2x1 or 4 1x1 connectors. If you have a good "ma & pa" type PC shop you can probably pick some ready made up from broken pc's that have had parts salvaged.